In systems for use in non-destructive testing of physical items and in other fields, non-invasive techniques are often required in order to determine conditions within an interior of a physical item. Ultrasonic vibrations have the capability of penetrating into and reflecting out of, or passing through, a solid physical item. By analyzing alterations in the patterns and frequencies of the ultrasonic vibrations after they have passed through a physical item, a visual image of the physical item, including features within the physical item, can be generated.
Specifically, an ultrasonic generator causes an emitter or transmitter element (transducer) to produce a directed sound field that propagates into a physical item to be tested. Reflections of defects or features within the physical item are directed back to a receiver element. The transmitter and receiver elements can be separate components within an array, or can be the same individual component functioning both as an transmitter and a receiver (referred to as a “transceiver”); similar to the manner in which a speaker can also function as a microphone. The sound field generates electrical impulses within the receiver. The electrical impulses are converted into data, which is processed, e.g., to create a visual image, or to create signals for inclusion in automated production environments. Phased-array transducers are used to provide a series of separate sound impulses (“tone bursts”) that can be separated in time from each other, to enable a directed sound field to be generated. For example, if an array of individual ultrasonic transducers is actuated so that tone bursts are emitted that are spaced apart in time a fixed amount between adjacent emitters, an angled planar sound wave can be generated.